1. Technical Field
This disclosure relates generally to polymeric fluids, such as silicones, mineral oils, and more particularly, to a process for fabricating a liquid polymer silicone having branched or linear molecular chains with added cross-linked networks.
2. Background Art
Polymer liquids, such as silicone oil and mineral oil, with high thermal stability and low surface tension have been widely used in the manufacture of semiconductors for various applications, including promoting formation of uniform structured film, improving liquid product flow and leveling, and increasing substrate wetting. However, the surface tension of silicone oil and mineral oil is below the average value of common surfaces, which restrict its applications in some particular areas, especially if the area needs stringent chemical migration controls. The disadvantages could include following aspects:
One disadvantage of low surface tension liquids is that it is hard to obtain desired film thickness and to control the wetting area on relevant substrates. Since most polymer liquids are formed by linear macromolecules or branched-linear macromolecules, the polymer chains are prone to sprawling on fresh substrate surfaces once applied. Symmetric chemical structure of silicone leads to low chemical polarity, which contributes to its low surface tension. On fresh substrate surfaces, the fluidic substances with relative lower surface tension have the tendency to cover (coat) its substrate surface for minimizing the internal energy of exposed surface. Over time, the polymer liquid ultimately reaches a thin layer with a relative thickness of a single polymeric macromolecule.
Another disadvantage of low surface tension liquids is that the migration to undesired regions of the surface can cause potential cross-contamination. Migratory liquid thin film could impair bonding adhesion strength to cause hermeticity issue of sealed multichip modules. For reworkable underfill application for MCMs (multichip modules), the uncontrollable wetting on glass ceramic substrates leads to insufficient amount of silicone fluid to underfill the chip C4 gap while thickness becomes critical. As such, alpha particle mitigation capability of reworkable underfill will be impaired during life-long MCM field system application.
On the other hand, fluidic characteristics need to be maintained for certain applications, such as thin gap filling, as well as removal once module repair needs to be done. In view of the foregoing, a need exists to overcome the disadvantages of currently used low surface tension liquids.